Semiconductor manufacturing apparatus

ABSTRACT

A semiconductor manufacturing apparatus includes an air distributor inside a chamber. The air distributor includes a first annular plate and a second annular plate disposed in an interior volume of the chamber, and an inner surface of the first annular plate and an inner surface of the second annular plate are connected to each other. A hollow region is defined by the first annular plate and the second annular plate. A gas through hole is extended from an outer surface of the first annular plate to the inner surface of the first annular plate. A plurality of ditches are between the inner surface of the first annular plate and the inner surface of the second annular plate, wherein the ditches are connected with the gas through hole and extended from the gas through hole to the hollow region to blow gas toward the hollow region.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 14/311,141,filed on Jun. 20, 2014, now allowed, which is incorporated by referencein its entirety.

BACKGROUND

Endpoint detection is a method adopted in semiconductor fabrication fordetecting a completion of a process in order to stop the process ontime. Various automated fabrication process may involve endpointdetection. For example, etching and/or deposition is known that anendpoint of an etching and/or deposition process may be determined bymonitoring a level of emission of selected byproducts of the etchingand/or deposition reaction. For example, an endpoint detector may beused for detecting byproducts of the etched and/or deposited layer inthe exhaust stream of the etching chamber. The etching process isstopped when no more byproduct is detected.

Endpoint detection may also rely on light emitted by the plasma duringthe etching reaction. This light includes emissions at wavelengthsrepresentative of specific substances present in the plasma. Therefore,the level of a reaction byproduct may be monitored through measurementof emissions at the byproduct's particular emission wavelength. Bymonitoring the level of a byproduct which may originate from the layerbeing treated by plasma, the endpoint of the process is indicated by asharp drop in the level of emitted reaction product. For example, in aplasma etching process wherein a layer of oxide is being removed, carbonmonoxide (CO) is a typical byproduct released into the plasma. CO emitslight at a wavelength of 483 nm. Therefore, when the oxide layer isfully removed, the CO emission decreases indicating the endpoint of theetch process.

However, the endpoint detection error is observed often time andsometime even causes wafer scrap because there is no endpoint beingdetected during a wafer patterning process. For the application oninsitu chamber cleaning, the over or under etching due to the endpointmissing may either damage the chamber or leave residues falling on thewafers. Therefore, for these problems to be solved, relevantdevelopments to advance the accuracy of detecting the endpoint areneeded.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isemphasized that, in accordance with the standard practice in theindustry, various features are not drawn to scale. In fact, thedimensions of the various features may be arbitrarily increased orreduced for clarity of discussion.

FIG. 1 is a cross sectional view of a semiconductor manufacturingapparatus having a chamber for accommodating a semiconductor waferduring operation in accordance with some embodiments of the presentdisclosure.

FIG. 2 is a perspective view of the air distributor in FIG. 1 inaccordance with some embodiments of the present disclosure.

FIG. 3 is an explosion view of the air distributor in FIG. 2 inaccordance with some embodiments of the present disclosure.

FIG. 4 is a perspective view of the air distributor in accordance withsome embodiments of the present disclosure.

FIG. 5 is an explosion view of the air distributor in FIG. 4 inaccordance with some embodiments of the present disclosure.

FIG. 6 is a perspective view of the air distributor in FIG. 2 along lineAA′ in accordance with some embodiments of the present disclosure.

FIG. 7 is a perspective view of the air distributor in FIG. 2 along lineBB′ in accordance with some embodiments of the present disclosure.

FIG. 8A and FIG. 8B are a perspective view of an air distributorconnected with gas lines in accordance with some embodiments of thepresent disclosure.

FIG. 9 is a perspective view of an air distributor with a tapered hollowregion in accordance with some embodiments of the present disclosure.

FIG. 10 is a perspective view of a quadrilateral air distributor inaccordance with some embodiments of the present disclosure.

FIG. 11A is an explosion view of the quadrilateral air distributor inFIG. 10 in accordance with some embodiments of the present disclosure.

FIG. 11B is a perspective view of the quadrilateral air distributor inFIG. 10 in accordance with some embodiments of the present disclosure.

FIG. 12 is a perspective view of a quadrilateral air distributor inaccordance with some embodiments of the present disclosure.

FIG. 13 is an explosion view of the quadrilateral air distributor inFIG. 12 in accordance with some embodiments of the present disclosure.

FIG. 14 is a perspective view of the air distributor in FIG. 12 alongline AA′ in accordance with some embodiments of the present disclosure.

FIG. 15 is a perspective view of the air distributor in FIG. 12 alongline BB′ in accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the invention.However, it will be understood by those skilled in the art that thepresent invention may be practiced without these specific details. Inother instances, well-known methods, procedures, components and circuitshave not been described in detail so as not to obscure the presentinvention. It is to be understood that the following disclosure providesmany different embodiments or examples for implementing differentfeatures of various embodiments. Specific examples of components andarrangements are described below to simplify the present disclosure.These are, of course, merely examples and are not intended to belimiting.

The making and using of the embodiments are discussed in detail below.It should be appreciated, however, that the present invention providesmany applicable inventive concepts that can be embodied in a widevariety of specific contexts. The specific embodiments discussed aremerely illustrative of specific ways to make and use the invention, anddo not limit the scope of the invention.

In the present disclosure, an apparatus is designed for varioussemiconductor manufacturing process such as dry etch or vapordeposition, especially for processes adopting plasma spectroscopy tomonitor chamber or wafer condition. Different types of chamber, such asPVD chamber, CVD chamber, or etching chamber may be applied by theapparatus. The apparatus is installed proximally to a sidewall of achamber to form an air curtain between chamber's inner space and anoptical emission spectroscopy (OES). The air curtain is designed toprevent any air stream flowing toward the OES, thus avoiding byproductsforming on a transparent cover on the sidewall of the chamber. Thelights emitted from the chamber are able to reach the OES withoutobstruction. Thus, the OES may detect the spectrum of plasma with highaccuracy.

The air distributor has at least one internal gas tunnel built insidethe distributor and connected to a gas through hole. Gas supplied fromsource external to the chamber is introduced into a hollow region of thegas distributor to form the air curtain by the internal gas tunnel.

FIG. 1 is a semiconductor manufacturing apparatus 100 having a chamber105 for accommodating a semiconductor wafer 132 during operation. Apedestal 120 is located in the chamber 105 for holding the wafer. Insome embodiments, the pedestal 120 is a heater. In some embodiments, thepedestal 120 is an electrostatic chuck (ESC). Gas is introduced intoinner space of the chamber 105 and ignited by a power source such asradio frequency (RF) generator to generate plasma. In some embodiments,the plasma is used to react with deposition film on the wafer in dryetch operation. Reactive gas such as CF₄, CCl₄, CF₃Cl, COF₂, SF₆, C₂F₆,C₃F₈, C₂F₄, CF₂, CF₃, CCl₃, F, Cl, Br, O (for resist), F₂, Cl₂, Br₂, isintroduced above the wafer 132 and energized by a top coil 103 togenerate ionized particles.

The ionized particles 20 dropped on the top surface of wafer 132 andreact with the atoms or molecules in the deposited film. Some inertgases such as nitrogen, argon or helium are also introduced into thechamber 105 as a carrier gas to distribute the ionized particles moreevenly in the chamber 105. Inert gas can be used in plasma etching as adiluent and a plasma stabilizer. Diluents may give a process controlvariable. For example, an inert gas can be added to increase a totalpressure while keeping partial pressures of other gases constant. Inaddition, some gas species can improve energy transfer from “hot”electrons to reactive gas molecules.

In some embodiments, the dry etch operation is performed in at least twostages. In the first stage, an OES 140 is used to monitor changes inchemical components inside the chamber 105. The OES 140 is connected toan optical fiber 180 that is attached near to a view port window 108 tocollect a certain wavelength of light emission with spectroscopy. Thechemical components change in the chamber 105 leads to changes ofintensity or color of the light emission into the OES 140. The OES 140sends an electrical signal to a computer that controls the chamber 105to stop the first stage. For example, at the end of a polysilicon etch,a silicon line intensity with wavelength around 2882 Å may be reduced bya lack of silicon supply. The change of the line intensity detected byOES 140 provides signal to the computer to end the silicon etch process.In some embodiments, the first stage is also called endpoint stagebecause the process duration is determined by a time when the certainwavelength of light emission ends. The first stage is followed by asecond stage. During the second stage, an extra etch time is introducedto further etches the wafer 132 to remove residues remained on the wafer132. Byproducts 25 are also generated in the chamber 105 during the dryetch operation. The byproducts 25 usually contain a compound consistingof materials from wafer surface and ionized particles 20 during filmremoval or recombination in the chamber 105. Some byproducts, such aspolymer are non-volatile and may grow in the chamber to form anunexpected film.

Typically, the dry etch operation is performed under a high vacuumenvironment, thus a transparent cover 110 is disposed proximally tochamber sidewall 107 to seal the view port window 108. In someembodiments as in FIG. 1, the transparent cover 110 has a size greaterthan the view port window 108. Light emission from inner space 105A ofthe chamber passes through the view port window 108 and the transparentcover 110 then arrives at the transparent cover 110. The optical fiber180 attached on the transparent cover 110 collects the emitted light andfurther transmits to the OES 140.

The transparent cover 110 is made with some materials resistant to theplasma formed in the chamber. Moreover, the suitable materials are alsotransparent to the wavelengths of lights emitted from the chamber 105.In some embodiments, non-metallic material such as quartz or sapphire isused as a cover to separate the optical fiber 180 from the view portwindow 108. In some embodiments, the non-metallic transparent cover 110is a ceramic material. The ceramic may be an oxide selected from a groupincluding aluminum oxide (Al₂O₃), titanium dioxide (TiO₂), niobiumpentoxide (Nb₂O₅), tantalum pentoxide (Ta₂O₅), cobalt tetroxide (Co₃O₄),chromium trioxide (Cr₂O₃), zirconium dioxide (ZrO₂), vanadium pentoxide(V₂O₅), magnesium oxide (MgO), yttria (Y₂O₃), etc. Surface of thematerial used for transparent cover 110 is anodized to possess a higherresistance to the reactive etchant in the plasma. A seal ring (notshown) is inserted between the transparent cover 110 and the sidewall107 to prevent gas leaking from the chamber 105.

In the present disclosure, an air distributor 150 is disposed betweenthe view port window 108 and inner space 105A. A side view of the airdistributor 150 as shown in FIG. 1 is a plate embedded in the chamberwall. The air distributor 150 is connected to a gas line 202 so as tosupply gas into the air distributor 150. In some embodiments, the gasline 202 is built in the chamber 105 and connected to a gas panel thatalso supplies other gases into the chamber 105. Some insert gases suchas helium, argon, or nitrogen is used as source of the air distributor150.

The air distributor 150 is made with materials resistant to the plasmaformed in the chamber 105. In some embodiments, the suitable materialsare non-metallic. In some embodiments, the non-metallic air distributor150 is made with a ceramic material. The ceramic material may be anoxide selected from a group including aluminum oxide (Al₂O₃), titaniumdioxide (TiO₂), niobium pentoxide (Nb₂O₅), tantalum pentoxide (Ta₂O₅),cobalt tetroxide (Co₃O₄), chromium trioxide (Cr₂O₃), zirconium dioxide(ZrO₂), vanadium pentoxide (V₂O₅), magnesium oxide (MgO), yttria (Y₂O₃),etc. Surface of the material used for air distributor 150 is anodized topossess a higher resistance to the reactive etchant in the plasma.

A pressure inside a view port window 108 should be constantly greaterthan a pressure inside an inner space 105A. Such condition is forkeeping out byproducts 25, ionized particles 20, or other gas particlesfrom reaching a transparent cover 110. For example, referring to FIG. 1,a view port window 108 may have a unit pressure control UPC 109 inside.An UPC 109 could sense the pressure inside a view port window 108. Insome cases, when an UPC 109 detects a decrease in a pressure inside aview port window 108, the UPC 109 would send a feedback signal to havegas line 202 increasing gas flows into the view port window.Furthermore, when an UPC 109 detects an increase in a pressure inside aview port window 108, the UPC 109 would send a feedback signal to havegas line 202 decreasing gas flows into the view port window. Thus theUPC 109 could maintain a stable pressure inside a view port window 108to keep a transparent cover 110 clean. For example, a view port window108 has a volume of about 250 cm³. A stability time of flow from airdistributor 150 may be about 15 seconds. Therefore, an UPC 109 maycontrol a flow rate of an inert gas to keep a pressure inside a viewport window 108 to be at a certain pressure. A flow rate of a gas isequal to a volume of the gas divided by a time the volume passesthrough. For example, an UPC 109 may control the flow rate of He gas tobe about 1,000 cm³/min. For different types of gas, such as Ne or Ar,different flow rate may be derived to obtain the certain pressure.

FIG. 2 is a perspective view of an air distributor 150 in accordancewith some embodiments of the present disclosure. The air distributor 150has a first annular plate 112 and a second annular plate 114. Surface112 a is a surface of the first annular plate 112 and facing toward thetransparent cover 110 when the air distributor 150 is installed on thesidewall 107 as in FIG. 1. The two annular plates are fastened againsteach other to form as an integrated disk with a hollow region 119 aroundcenter. When the air distributor 150 is installed in the chamber. Thehollow region 119 is aligned with the transparent cover 110 to provide aclear see-through for the optical fiber 180 to collect the lightemission from chamber 105. In some embodiments, size of the hollowregion 119 is greater or substantially same as the transparent cover 110such that light emitted from the chamber 105 is not blocked by the airdistributor 105.

A pair of gas through holes 116 is located symmetrically on the surface112 a of the first annular plate 112. In some embodiments, the gasthrough holes 116 are not arranged in a symmetrical manner on thesurface 112 a. Each gas through hole 116 is connected to a gas line 202like in FIG. 1 when the air distributor 150 is installed in a chamber.In some embodiments, there are more or less than two through holes in anair distributor.

FIG. 3 is an explosion view of the air distributor 150 in FIG. 2. Thefirst annular plate 112 and the second annular plate 114 respectivelyhave six through holes (number of through hole varies according todifferent embodiments). In some embodiments, the through holes in thefirst or second annular plate are threaded. The through holes on eachplate are aligned with another plate. A bolt 115 is screwed into alignedthrough holes such as 112 h and 114 h to fasten the first annular plate112 and the second annular plate 114.

FIG. 4 is a perspective view of the air distributor 150 in FIG. 2flipped. The second annular plate 114 is facing upward. A surface 114 aof the second annular plate 114 is flat and toward the inner space 105Aof the chamber 105 when the distributor is installed in the chamber 105as in FIG. 1. The assembled air distributor 150 has a hollow region 119around the center.

FIG. 5 is an explosion view of the air distributor in FIG. 4. Anothersurface 112 b of the first annular plate 112 is revealed. The surface112 b is opposite to the surface 112 a in FIG. 3 and interfaced with thesecond annular plate 114. There are several ditches 127 connected to agas through hole 116. The ditches 127 are recessed under the surface 112b and each ditch 127 extends from the gas through hole 116 to the hollowregion 119 of the first annular plate 112. Gas from the gas through hole116 is guided by the ditches 127 and further flows into the hollowregion 119. In the present embodiments, each gas through hole 116 isconnected with five ditches 127. There are ten ditches 127 arrangedsymmetrically on the surface 112 b. Gas is introduced into the hollowregion 119 by the ditches 127 and distributed evenly to form a showercurtain.

FIG. 6 is a perspective view along line AA′ of the air distributor 150in FIG. 2. The first annular plate 112 is tightened to be against thesecond annular plate 114. Each ditch 127 has an open end 127 a at theedge of the open region 119 and toward the open region 119. The openends 127 a are distributed symmetrically around the edge of the openregion 119. In some embodiments, the open end 127 a is a semicircle andeach open end 127 a has a same cross sectional area. FIG. 7 is aperspective view along line BB′ of the air distributor 150 in FIG. 2. Insome embodiments, a portion of the surface 114 b is also carved to formseveral ditches and the ditches are arranged on the surface 114 b in apattern corresponding to the ditches 127 on surface 112 b. The firstannular plate 112 is assembled with the second annular plate 114, andthe ditch 127 and its corresponding ditch on the second annular plate114 form a tunnel inside the air distributor 150. In some embodiments,the tunnel inside the air distributor 150 is cylindrical.

FIG. 8A is a drawing showing an air distributor 150 under operation.Each gas through hole 116 of first annular plate 112 is connected to agas line 202. The gas is supplied from a source such as a gas panel 315.Gas flows through the gas ling 202 and into a corresponding gas throughhole 116. Gas is further introduced into the hollow region 119 by theditches 127 inside the air distributor 150. The dotted arrow linestoward the center of hollow region 119 represent streams of gas releasedfrom the open ends 127 a. Streams of released gas form an invisiblepartition wall or air curtain to separate etchant gas or byproducts onone side of the air distributor 150 from another side of the airdistributor 150. The invisible partition wall or air curtain preventbyproduct from depositing on the transparent cover 110 on chambersidewall 107 in FIG. 1.

In some embodiments, the inner edge of the first annular plate 112 orthe second annular plate 114 is modified to guide the gas released fromditches toward the inner space 105A of chamber 105 in FIG. 1. As in FIG.9, the inner edge of the air distributor 105 is tapered. The airdistributor 105 has a central hollow region 119 with circular shape. Thecentral hollow region 119 has a first opening 119 a facing the chamberinner space 105A. A second opening 119 b opposite to the first opening119 facing the transparent cover 110. The first opening 119 a has anarea greater than the opening 119 b. Gas released from the ditches formsan air curtain with a positive pressure toward the inner space 105A. Theair curtain is designed to blow into the inner space 105A such that nobyproducts are allowed to pass the air distributor 105. In someembodiments, the tapered angle of the inner edge is between about 5degrees and about 15 degrees.

Referring to FIG. 8B, in some embodiments, there are two gas panels 315.One gas penal may operate to blow gas through a gas line 202 and into acorresponding gas through hole 116. Gas is further introduced into ahollow region 119 by several ditches 127 inside an air distributor 150.Another gas penal may operate to suck gas through another gas line 202from another corresponding gas through hole 116. Gas is further suckedfrom a hollow region 119 by several ditches 127 inside an airdistributor 150.

In some embodiments, the gas introduced into the air distributor ishelium that is supplied from a same source of the gas for cooling wafer132 in FIG. 1. During plasma dry etch, wafer 132 on the pedestal 120 isheated during ion bombardment, thus a helium gas is introduced to thebackside of wafer 132 to bring wafer temperature down to an acceptablerange. In some embodiments, the pedestal 120 is an electrostatic chuck(ESC) used to hold a wafer during the dry etch operation.

In addition to the dry etch operation, endpoint mode etch is alsoadopted to remove deposition film in a vapor deposition chamber. Forexample, in a chemical vapor deposition (CVD) chamber, thin films suchas silicon oxide or silicon nitride are grown on the chamber inner wallas well as on the wafer. A plasma etch is used to clean the filmsbuildup on the inner wall. In some embodiments, a similar OES and viewport window as in FIG. 1 are implemented in the CVD chamber to detectthe spectroscopy of the emission light during plasma clean in order tooptimize the clean time. The air distributor 150 as in FIG. 1 is used toform an air curtain during clean. Therefore, the byproducts duringplasma clean are unable to reach the transparent cover 110.

Monitoring of a plasma cleaning processes may be accomplished throughoptical emission spectroscopy (OES), a technique by which light emittedby a process, such as a plasma etch within chamber, is analyzed to seewhich wavelengths are present in the light. Different types of plasmachamber, such as PVD chamber, CVD chamber, or etching chamber may beapplied by the plasma cleaning processes. Inferences about the processmay then be drawn as a result of the intensity of various spectral linespresent in the light. For example, presence of certain species withinthe chamber may be ascertained because each kind of molecule or atom hasa characteristic optical emission at specific wavelengths (opticalemission spectrum). When cleaning plasma reacts with accumulatedbyproducts 25, related product species are formed and may be identifiedby their unique and characteristic optical emission. After theaccumulated byproducts 25 have been removed from a chamber and thechamber sidewall 107 are exposed to the plasma, there is a change in theoptical emission. This change in optical emission can be used to detectan endpoint of the cleaning process.

A time-mode technique could be used for detecting the endpoint of plasmaclean. The cleaning process is performed for a fixed period of timeestimated to remove the byproducts 25 accumulated on the chambersidewall 107. Thus, it is obvious that either under-cleaning orover-cleaning is likely to occur. Under-cleaning may lead to particleproblems and degradation of processing stability. Over-cleaning resultsin the highly reactive cleaning gases attacking the chamber sidewall 107and shortening its lifetime. Further, expensive cleaning gases may bewasted and cleaning time is not optimized.

Besides the aforementioned dry etch and CVD chamber, other tools use OESto monitor process or clean status are within the contemplated scope ofthe present disclosure.

The air distributor 150, as in FIG. 2 and FIG. 4, is in circular shape.However, in the present disclosure, it should not be deemed as alimitation. As in FIG. 10, an air distributor 450 is in quadrilateralshape. FIG. 11A is an explosion view of the air distributor 450 in FIG.10. The air distributor 450 has a first annular plate 412 and a secondannular plate 414. Both annular plates are quadrilateral and each hastwelve through holes. In some embodiments, the through holes in thefirst or second annular plate are threaded. Similar to the circular typeair distributor, a bolt 115 is screwed into through hole 412 h and 414 hto fasten the first annular plate 412 against to the second annularplate 414. In some embodiments, the size of the first annular plate 412is same with the second annular plate 414.

Surface 414 b is toward an inner space of a chamber while the airdistributor 450 is installed in the chamber. In some embodiments, thechamber is configured for a plasma operation, for example reactive ionplasma etch or a CVD deposition. The plasma operation includes plasmaetch or plasma clean.

The hollow region 119 is configured to form an air curtain when the airdistributor 450 is in operation. Gas introduced into the air distributor450 is guided by the ditches 427 into the hollow region 119. The ditches427 are recessed from a surface 412 a of the first annular plate 412. Insome embodiments, the ditches 427 are arranged around the quadrilateralhollow region 119 as in FIG. 11A. In some embodiments, the hollow region119 is at a central portion of the air distributor 119.

FIG. 12 is a perspective view of the air distributor 450 in FIG. 10flipped. The first annular plate 412 is clamped with the second annularplate 414. The end 427 a of each ditch 427 in the first plate 412 inFIG. 11A is exposed. The ditches 427 are tunnels to guide gas from gasthrough hole 416 into the hollow region 119. In some embodiment, oneside of the hollow region 119 may have several ditch ends for blowinggas into the hollow region 119, and an opposite side may have severalditch ends for sucking gas from the hollow region 119 as shown in FIG.11 B.

FIG. 13 is an explosion view of the air distributor 450 in FIG. 12. Inthe drawing, on one side of the hollow region 119, there are three ditchends 427 a, and on the other side, there is one ditch end 427 a. In someembodiments, each side has a same number of ditch ends and symmetricallyarranged around the edge of the hollow region.

FIG. 14 is a perspective view of the air distributor 450 in FIG. 12 cutalong line AA′. Each ditch 427 has an open end 427 a at the edge of theopen region 119 and toward the open region 119. The open ends 427 a aredistributed symmetrically around the edge of the open region 119. Insome embodiments, the open end 427 a is a semicircle and each open end427 a has a same cross sectional area.

FIG. 15 is a perspective view of the air distributor 450 in FIG. 12 cutalong line BB′. In some embodiments, a portion of the surface 414 b isalso carved to form several ditches and the ditches are arranged on thesurface 414 b in a pattern corresponding to the ditches 427 on surface412 b. The first annular plate 412 is assembled with the second annularplate 414, and the ditch 427 and its corresponding ditch on the secondannular plate 414 form a tunnel inside the air distributor 450. In someembodiments, the tunnel inside the air distributor 450 is cylindrical.

In some embodiments, the first annular plate has a same thickness of thesecond annular plate and each annular plate has a ditch. In someembodiments, the air distributor has more than one hollow region aroundthe center region. Each hollow region is connected to a ditch for gasintroduction.

A semiconductor manufacturing apparatus includes a chamber configuredfor plasma etching, a view port window on a sidewall of the chamber andconfigured to receive an optical emission spectroscopy (OES); and an airdistributor located between the view port window and an inner space ofthe chamber. The air distributor includes a hollow region aligned withthe transparent window and configured to generate an air curtain in thehollow region to isolate the view port from the inner space.

In many plasma etching systems an endpoint of an etching or a depositingprocess is detected using a light or an optical sensor, such as an OES140, and a digital computer in controller. Typically, the optical sensoris set up, using narrow band pass filters, to monitor an intensity oflight at a single characteristic wavelength associated with severalreaction products produced by etching a layer or to monitor intensity oflight at a wavelength associated with several gaseous reactants inplasma used to etch the layer. An accumulation of a gas depositing onthe transparent cover 110 may alter some amount of light received by anOES 140, and thus may obscure a reading of the intensity of light at asingle characteristic wavelength. The intensity of light is used forgenerating a derived value. The digital computer then compares severalderived values, derived from the wavelength and intensity of light to aspecified threshold value. Once the threshold has been exceeded, thedigital computer determines when a specified endpoint of the etching orthe depositing process has been reached. There may be several ways todetermine the specified endpoint. One way may be to compare the valueswith the specified threshold value. Another way may be to compare aslope of a change in the values with a specified threshold slope. A userspecifies which way is used to detect an endpoint prior to initiating anetching process.

An endpoint can be specified by several methods. One method specifiesthe endpoint as a point at which some certain number of derived valuesor slopes exceed a specified threshold and consecutively increase inmagnitude. Another method specifies the endpoint as a point at which acertain number of derived values or slopes exceed a specified thresholdand have consecutively decreased from a peak of those values. Yet,another method specifies the endpoint as a point at which a specifiednumber of derived values or slopes are below a specified threshold andare consecutively decreasing, but only after the derived values orslopes has at least once exceeded the specified threshold.

Not only is keeping an intensity of light continuously without obscuringan important factor in determining an endpoint of a process insemiconductor manufacture, detail resolution about an intensity of lightat various spectral lines present in the light may also be an importantconsideration. Because different plasma gas may produce differentspectral lines. A precise measurement for various spectral lines mayallow controlling of multiple processes simultaneously.

Dry etch differs from wet etch in that it usually does not have goodetch selectivity to an underlying layer. Endpoint detection systemsmeasure different parameters, such as a change in the etch rate, sometypes of etch products removed from an etch process, or change inseveral active reactants in a gas discharge. Emission intensity isdirectly related to a relative concentration of a species in plasma. Inthis manner the endpoint detector can determine when a reaction processis complete and proceeded into the underlying layer.

An example of a situation in which precise endpoint detection isimportant in fabricating MOS transistors is a processing step in which athin “spacer” is formed adjacent to an MOS transistor gate. A siliconoxide film is deposited over a polysilicon gate that was defined by aprior etch step. Some results of properly terminated plasma etch of thesilicon oxide film, producing silicon oxide spacers on all sides of thepolysilicon gate. A channel width of the transistor may be governed by awidth of the silicon oxide spacers. if the plasma etching of the siliconoxide layer is allowed to continue past its ideal endpoint, the siliconoxide spacers will be thinner than is ideal and resulting transistorchannel width will be shorter than a channel width that was supposed tobe produced.

An obscuring by an accumulation of a gas depositing on transparent cover110 may not only diminish an intensity of light but may also increase anintensity of light. For example, some false peaks may be created bynoise, which may exceed a threshold for some very small period of time.Some process may be design to stop as light intensity reaches certainpeak value. As a result OES 140 will cause the process to be endedprematurely by detection of a false endpoint. Data about an intensity oflight may go through various analyzing such as digital filtering,cross-correlating, normalization, or average normalization. Therefore,exactness about the intensity of light is indispensable to permit a veryfine control of a processing time. Improvement of endpoint detectionwith air curtain is capable of being implemented on known chambers.

A semiconductor manufacturing apparatus includes a chamber, a view portwindow on a sidewall of the chamber and configured to receive an opticalemission spectroscopy (OES); and an air distributor located between theview port window and an inner space of the chamber. The air distributorincludes a hollow region aligned with the transparent window andconfigured to generate an air curtain in the hollow region to isolatethe view port from the inner space.

In some embodiments, the air distributor is in the sidewall of thechamber.

In some embodiments, the air distributor includes anodized non-metallicmaterial.

In some embodiments, the air distributor includes a gas inlet configuredfor receiving an inert gas.

In some embodiments, the air distributor includes a first annular plateinterfaced with a second annular plate, the first annular plate and thesecond annular plate are fastened against each other with a bolt.

In some embodiments, the semiconductor manufacturing apparatus furtherincludes a ditch on a surface of the first annular plate or the secondannular plate, wherein the ditch is configured to be a gas flow path.

In some embodiments, the air distributor includes an internal tunnel,the internal tunnel includes a first end toward the hollow region and asecond end configured for receiving an inert gas.

In some embodiments, the view port window has an area substantially sameto an area of the hollow region.

In some embodiments, the semiconductor manufacturing apparatus furtherincludes a quartz plate sealed at the view port window.

In some embodiments, the OES is an endpoint detector.

In some embodiments, the view port window includes a unit pressurecontrol.

A semiconductor manufacturing apparatus includes a chamber, a pedestalfor receiving a wafer and located in the chamber, a window on a sidewallof the chamber and configured to receive an optical emissionspectroscopy (OES) of light emission from the chamber; and an airdistributor between the window and the pedestal, wherein the airdistributor has a hollow region configured to have an air curtain formedtherein.

In some embodiments, the air distributor is embedded in a wall of thechamber.

In some embodiments, the air distributor includes a gas through holeconfigured to connect with a gas line.

In some embodiments, the semiconductor manufacturing apparatus furtherincludes a gas line.

In some embodiments, the air distributor is shaped in polygonal, orcircular.

In some embodiments, the air distributor has a gas tunnel inside the airdistributor and connected with a gas through hole, and the gas throughhole is on a surface of the air distributor.

In some embodiments, the air distributor has a gas tunnel inside the airdistributor and the gas tunnel is extended to the hollow region.

A semiconductor manufacturing apparatus includes an air distributorinside a chamber, wherein the air distributor includes, a first annularplate and a second annular plate bolted through a through hole, a gasthrough hole in the first annular plate and the gas through holeextending from a first surface of the first annular plate to a secondsurface of the first annular plate, a ditch on the second surface of thefirst plate and connected with the gas through hole on the secondsurface of the first plate; wherein the ditch extends from the gasthrough hole to a center hollow region of the first plate. In someembodiments, the chamber is configured for an etching operation.

In some embodiments, the semiconductor manufacturing apparatus furtherincludes a ditch on a surface of the second annular plate, wherein thesurface is against to the second surface of the first annular plate.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, and composition of matter, means, methods and stepsdescribed in the specification. As those skilled in the art will readilyappreciate form the disclosure of the present disclosure, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present disclosure.

Accordingly, the appended claims are intended to include within theirscope such as processes, machines, manufacture, and compositions ofmatter, means, methods or steps. In addition, each claim constitutes aseparate embodiment, and the combination of various claims andembodiments are within the scope of the invention.

What is claimed is:
 1. A semiconductor manufacturing apparatus,comprising: a chamber; and an air distributor inside a chamber, whereinthe air distributor includes: a first annular plate and a second annularplate disposed in an interior volume of the chamber, wherein an innersurface of the first annular plate and an inner surface of the secondannular plate are connected to each other; a hollow region defined bythe first annular plate and the second annular plate; at least one firstgas through hole and at least one second gas through hole extended froman outer surface of the first annular plate to the inner surface of thefirst annular plate; and a plurality of first ditches and second ditchesbetween the inner surface of the first annular plate and the innersurface of the second annular plate, wherein the first ditches areconnected with the at least one first gas through hole and extended fromthe at least one first gas through hole to the hollow region to blow gastoward the hollow region, and the second ditches are connected with theat least one second gas through hole and extended from the at least onesecond gas through hole to the hollow region to such gas from the hollowregion, wherein the first ditches and the second ditches are arrangedsymmetrically around edges of the hollow region.
 2. The semiconductormanufacturing apparatus of claim 1, wherein the edges of the hollowregion comprise tapered edges.
 3. The semiconductor manufacturingapparatus of claim 1, wherein the at least one first gas through holeand the at least second gas through hole are arranged symmetrically. 4.A semiconductor manufacturing apparatus, comprising: an air distributorinside a chamber, wherein the air distributor includes: a first annularplate and a second annular plate disposed in an interior volume of thechamber, wherein an inner surface of the first annular plate and aninner surface of the second annular plate are connected to each other; ahollow region defined by the first annular plate and the second annularplate; at least one gas through hole extended from an outer surface ofthe first annular plate to the inner surface of the first annular plate;and a plurality of ditches between the inner surface of the firstannular plate and the inner surface of the second annular plate, whereinthe ditches are connected with the at least one gas through hole andextended from the at least one gas through hole to the hollow region toblow gas toward the hollow region.
 5. The semiconductor manufacturingapparatus of claim 4, further comprising: a view port window on asidewall of the chamber and configured to receive an optical fiber; andan optical emission spectroscopy (OES) external to the chamber andconnected with the optical fiber;
 6. The semiconductor manufacturingapparatus of claim 5, further comprising a transparent cover disposed atthe view port window.
 7. The semiconductor manufacturing apparatus ofclaim 4, wherein the air distributor is protruded from a sidewall of thechamber to the interior volume of the chamber.
 8. The semiconductormanufacturing apparatus of claim 4, wherein the air distributor includesanodized non-metallic material.
 9. The semiconductor manufacturingapparatus of claim 4, further comprising at least one gas line connectedwith the at least one gas through hole.
 10. The semiconductormanufacturing apparatus of claim 9, further comprising a gas panelconnected to the at least one gas through hole and configured to supplygas to the hollow region through the at least one gas line, the at leastone gas through hole and the plurality of ditches.
 11. The semiconductormanufacturing apparatus of claim 10, wherein the gas panel comprises aninert gas panel configured to supply inert gas to the hollow regionthrough the at least one gas line, the at least one gas through hole andthe plurality of ditches.
 12. A semiconductor manufacturing apparatus,comprising: an air distributor inside a chamber, wherein the airdistributor includes: a first annular plate and a second annular platedisposed in an interior volume of the chamber, wherein an inner surfaceof the first annular plate and an inner surface of the second annularplate are connected to each other; a hollow region defined by the firstannular plate and the second annular plate; at least one first gasthrough hole and at least one second gas through hole extended from anouter surface of the first annular plate to the inner surface of thefirst annular plate; and a plurality of first ditches and second ditchesbetween the inner surface of the first annular plate and the innersurface of the second annular plate, wherein the first ditches areconnected with the at least one first gas through hole and extended fromthe at least one first gas through hole to the hollow region to blow gastoward the hollow region, and the second ditches are connected with theat least one second gas through hole and extended from the at least onesecond gas through hole to the hollow region to such gas from the hollowregion.
 13. The semiconductor manufacturing apparatus of claim 12,further comprising: a view port window on a sidewall of the chamber andconfigured to receive an optical fiber; and an optical emissionspectroscopy (OES) external to the chamber and connected with theoptical fiber;
 14. The semiconductor manufacturing apparatus of claim13, further comprising a transparent cover disposed at the view portwindow.
 15. The semiconductor manufacturing apparatus of claim 12,wherein the air distributor is protruded from a sidewall of the chamberto the interior volume of the chamber.
 16. The semiconductormanufacturing apparatus of claim 12, wherein the air distributorincludes anodized non-metallic material.
 17. The semiconductormanufacturing apparatus of claim 12, further comprising at least onefirst gas line connected with the at least one first gas through hole,and at least one second gas line connected with the at least one secondgas through hole.
 18. The semiconductor manufacturing apparatus of claim17, further comprising a first gas panel connected to the at least onefirst gas through hole and configured to supply gas to the hollow regionthrough the at least one first gas line, the at least one first gasthrough hole and the plurality of first ditches.
 19. The semiconductormanufacturing apparatus of claim 18, wherein the first gas panelcomprises an inert gas panel configured to supply inert gas to thehollow region through the at least one first gas line, the at least onefirst gas through hole and the plurality of first ditches.
 20. Thesemiconductor manufacturing apparatus of claim 18, further comprising asecond gas panel connected to the at least one second gas through holeand configured to suck gas from the hollow region through the pluralityof second ditches, the at least one second gas through hole and the atleast one second gas line.